1. Field of the Invention
Embodiments of the present invention generally relate to methods of making write poles for perpendicular magnetic recording write heads.
2. Description of the Related Art
Perpendicular magnetic recording systems are utilized in computer hard disk drives. A typical perpendicular recording write head includes a trailing write pole, a leading return or opposing pole magnetically coupled to the write pole, and an electrically conductive magnetizing coil around the write pole. The magnetic fields of bits of stored information are oriented normal to the plane of the thin film of media, and thus, perpendicular to the direction of a circular data track.
For the magnetic write pole, the width of the pole at the air bearing surface (ABS) affects the areal density. The increasing of areal density benefits mainly by decreasing the width of the magnetic write pole at the ABS. FIGS. 3A-3D exemplify a prior art method of fabricating a narrow width write pole. A layer (or layers) of laminated magnetic materials 304 is deposited over a substrate 302. For simplicity, the laminated structure is shown as a single layer 304. Over the layer of magnetic material 304, a layer (or layers) of non-magnetic film is deposited as an ion mill hard mask 305. For simplicity again, the layers of the non-magnetic film are shown as a single layer 305. A polymeric underlayer 306 is spin coated on the non-magnetic mill hard mask 305, and a dielectric hard mask layer 308 is deposited on the polymeric underlayer. A photoresist mask 310 is then formed over the dielectric layer 308. The dielectric layer 308 is then patterned by a first reactive ion etching (RIE) process using the photoresist mask 310 to form a dielectric hard mask 312. A portion of the photoresist mask is consumed in this first RIE process. The polymeric underlayer 306 is then patterned by a second RIE process using the dielectric hard mask 312 to expose the layer of non-magnetic mill mask layer 305. The photoresist mask is completely consumed during the second RIE process. The patterned polymeric underlayer 306 is then used as a mask for milling the layer of non-magnetic mill mask layer 305 and then magnetic material 304 to bevel the layer of magnetic material 304 to an angle θ from the patterned polymeric underlayer 306 to the substrate 302. An angle θ of up to about 10 degrees can be obtained on a consistent basis with a proper mill process control.
Angles of up to about 10 degrees are acceptable for current generation magnetic write heads. However, higher bevel angles are needed for the next and future generations of magnetic write heads.